XPost: sci.electronics.design   
   From: jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net   
      
   West wrote:   
      
   > Using a 555 or similar type chip, I would like to have the output change   
   > from low to high or high to low every time the system is turned on. IOW, the   
   > output is a high, then the system is turned off. When the system is turned   
   > back on, the output goes low. Each power up of the circuit changes or   
   > "flips" the output state. I am willing to incorporate CMOS and a battery   
   > back up in the design. Some of the ideas I entertained is a divide by 2 in   
   > front of the toggle, giving me the same state every other time. However, I'm   
   > not sure how to do this practically or if it's the way to go. Any   
   > suggestions out there? All comments welcomed and thanks.   
   >   
   > west   
   >   
   >   
   Don't know your application how ever..   
     they make latching relays..   
      
       Get one with a DPDT set of contacts. One pole will be   
   used to signal the direction to switch a monostable   
   type circuit composed of 2 transistors with a few   
   minor components added.   
      The relay has 2 coils and thus are used as the collector   
   load side resisters for the monostable circuit.   
      
     The set of contacts you'll be using will have a resister   
   connected to the Center Pole while the outer contacts,   
   each being connected to the base of a transistor..   
      The idea is to create a slight offset so that the monostable   
   will favor a side. Because there is induction involved   
   here, the circuit will be fully on position before the coil even   
   starts the create current. So this means when the contacts do open   
   to change sides, the unloading effect will not alter the operation.   
      
       That will retain the last position with out the use   
   of constant power.   
       Of course, you didn't specify the working cycle rate you   
   expect to get. These relays are mechanical so take it from there.   
      
      This is an old trick I have used for years for alternating   
   a state from a single source point for basic stuff.   
      
      
      
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   "I'd rather have a bottle in front of me than a frontal lobotomy"   
   http://webpages.charter.net/jamie_5   
      
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